Ferrule for optical connector and process for making same

A ferrule for optical connector, which is to be mounted to a distal end of an optical fiber, comprising:

• an opening portion provided in a back face of the ferrule, for introducing the distal end of said optical fiber into a first space inside the ferrule from the outside;
• a first grip portion arranged along an insertion direction of said optical fiber and opposed to said opening portion through said first space, said first grip portion having a first through hole for the optical fiber set through said opening portion to be further introduced therethrough, gripping part of said optical fiber apart a predetermined distance from the distal end of said optical fiber, and partitioning a space inside the ferrule into said first space and a second space;
• a second grip portion located to constitute a front face of the ferrule along the insertion direction of said optical fiber and opposed to said first grip portion through said second space, said second grip portion having a second through hole for the optical fiber set through said first through hole to be further introduced therethrough and gripping the vicinity of the distal end of said optical fiber;
• and
• a first pedestal portion projecting from a surface of said first grip portion, which is opposed to said opening portion through said first space, said first pedestal portion having a guide surface for guiding the distal end of the optical fiber inserted through said opening portion into said first space, into the first through hole of said first grip portion.

A ferrule for optical connector, which is to be mounted to a distal end of a fiber tape in which a plurality of optical fibers are incorporated with a coating and into which bare optical fibers exposed by removing said coating by a predetermined distance from the distal end of said fiber tape are to be inserted, said ferrule for optical connector comprising:

• an opening portion provided in a back face of the ferrule, for introducing distal ends of said plurality of bare optical fibers into a first space inside the ferrule from the outside;
• a first grip portion arranged along an insertion direction of said optical fibers and opposed to said opening portion through said first space, said first grip portion having a plurality of first through holes for the optical fibers set through said opening portion to be further introduced therethrough, gripping a part of each of said optical fibers apart a predetermined distance from the distal ends of said optical fibers, and partitioning a space inside the ferrule into said first space and a second space;
• a second grip portion located to constitute a front face of the ferrule along the insertion direction of said optical fibers and opposed to said first grip portion through said second space, said second grip portion having a plurality of second through holes for the optical fibers set through said first grip portion to be further introduced therethrough and gripping the vicinity of the distal ends of said optical fibers;
• and
• a first pedestal portion projecting from a surface of said second grip portion, which is opposed to said first grip portion through said second space, toward said first grip portion, said first pedestal portion having a support face opposed to a portion of a predetermined length of said each optical fiber along an arrangement direction of said second through holes.

A process for producing a ferrule for an optical connector, comprising the steps of:

• preparing upper and lower dies, each having a recessed portion of predetermined shape so that a ferrule forming cavity is defined when main surfaces of the dies are brought together while pinching core pins for forming through holes for insertion of optical fibers,
• wherein the upper die has a first upper grip portion for gripping the vicinity of distal ends of the core pins, the first grip portion being provided at a predetermined position in the main surface of the upper die, and a second upper grip portion for gripping a predetermined part of the core pins apart a predetermined distance from the distal ends of the core pins, the second upper grip portion having a grip face for pushing the predetermined part of the core pins and normally projecting from a bottom part of the recessed portion of the upper die surrounded by the main surface of the upper die,
• wherein the lower die comprises a first lower grip portion for gripping the vicinity of the distal ends of the core pins together with the first upper grip portion, the first lower grip portion being provided at a position coincident with the position of the first upper grip portion when the upper die and the lower die are brought into close fit while pinching the core pins for forming the through holes for insertion of optical fibers, and a second lower grip portion for gripping a part of the core pins together with the second upper grip portion, the second lower grip portion normally projecting from a bottom part of the recess portion of the lower die and having a grip face opposed to the grip face of the second upper grip portion when the upper and lower dies are brought together while pinching the core pins for forming the through holes for insertion of optical fibers, and
• wherein the length in the insertion direction of the core pins, of the grip face provided in the second lower grip portion is greater than a length in the insertion direction of the core pins, of the grip face provided in the second upper grip portion;
• bringing the upper and lower dies together;
• pouring a resin into the cavity formed by the recessed portions of the upper and lower dies through a gate defined by the upper and lower dies, thereby resin-molding the ferrule;
• allowing the resin to solidify;
• withdrawing the core pins;
• and
• separating the upper and lower dies to obtain a ferrule for optical connector resin-molded in a same shape as the cavity.